Unable to increase partition after storage upgrade on VPS

Hi, some week ago I have upgraded my VPS from 40GB to 80GB storage. The VPS have Debian 10 with ext4 partition.

I followed the guide indicating how to expand partition, but differently from how is indicated, from recovery mode, I can see my partition only being 40gb, and NOT 80Gb (or extra free space over 40Gb).

This is my lsblk command from rescue mode (sda1 was rescue temporary partition, sdb1 the main partition):

> [RESCUE] root@vps-8b56af31:~ $ lsblk
> NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
> sda 8:0 0 2.5G 0 disk
> └─sda1 8:1 0 2.5G 0 part /
> sdb 8:16 0 40G 0 disk
> └─sdb1 8:17 0 40G 0 part

The fdisk command say only 40Gb too:
> Command (m for help): p
> Disk /dev/sdb: 40 GiB, 42949672960 bytes, 83886080 sectors

I have searched in Google other users who had done this operation, and from thei log at this point they see the new space.

But by OVH API and OVH pannel, the disk seems ok....

> {
>
> keymap: null
> memoryLimit: 4096
> -
> model: {
> version: "2019v1"
> name: "vps-essential-2-4-80"
> disk: 80
> datacenter: [ ]
> vcore: 2
> memory: 4096
> maximumAdditionnalIp: 16
> availableOptions: [ ]
> offer: "VPS vps2020-essential-2-4-80"
> }
> name: "omissis"
> zone: "Region OpenStack: os-de2"
> slaMonitoring: false
> cluster: ""
> vcore: 2
> displayName: "omissis"
> monitoringIpBlocks: [ ]
> offerType: "ssd"
> netbootMode: "local"
> state: "running"
> }

I have opened a ticket in OVH, but they responde me who they can not intervene on the OS of the user....
I have asket to others system engineers, and they say who seems something went wrong during upgrade and that ovh must intervene on the vps to resolve.

Are we missing something? What do I have to do? I urgently need new space on my vps...
This is the full log of a partition expansion attempt, which failed:

> GNU/Linux, to the rescue!
>
> Server: vps-8b56af31
> Login: root
> Password: TxBHSDB7X9Gr
>
> [RESCUE] root@vps-8b56af31:~ $ lsb
> lsblk lsb_release
> [RESCUE] root@vps-8b56af31:~ $ lsblk
> NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
> sda 8:0 0 2.5G 0 disk
> └─sda1 8:1 0 2.5G 0 part /
> sdb 8:16 0 40G 0 disk
> └─sdb1 8:17 0 40G 0 part
> [RESCUE] root@vps-8b56af31:~ $ e2fsck -yf /dev/sdb1
> e2fsck 1.44.5 (15-Dec-2018)
> Pass 1: Checking inodes, blocks, and sizes
> Pass 2: Checking directory structure
> Pass 3: Checking directory connectivity
> Pass 4: Checking reference counts
> Pass 5: Checking group summary information
> /dev/sdb1: 1667141/2621440 files (0.7% non-contiguous), 9076357/10485504 blocks
> [RESCUE] root@vps-8b56af31:~ $ fdisk -u /dev/sdb
>
> Welcome to fdisk (util-linux 2.33.1).
> Changes will remain in memory only, until you decide to write them.
> Be careful before using the write command.
>
>
> Command (m for help): p
> Disk /dev/sdb: 40 GiB, 42949672960 bytes, 83886080 sectors
> Disk model: QEMU HARDDISK
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disklabel type: dos
> Disk identifier: 0x05337b4e
>
> Device Boot Start End Sectors Size Id Type
> /dev/sdb1 * 2048 83886079 83884032 40G 83 Linux
>
> Command (m for help): d
> Selected partition 1
> Partition 1 has been deleted.
>
> Command (m for help): n
> Partition type
> p primary (0 primary, 0 extended, 4 free)
> e extended (container for logical partitions)
> Select (default p): p
> Partition number (1-4, default 1): 1
> First sector (2048-83886079, default 2048): 2048
> Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-83886079, default 83886079):
>
> Created a new partition 1 of type 'Linux' and of size 40 GiB.
> Partition #1 contains a ext4 signature.
>
> Do you want to remove the signature? [Y]es/[N]o: n
>
> Command (m for help): a
>
> Selected partition 1
> The bootable flag on partition 1 is enabled now.
>
> Command (m for help): w
> The partition table has been altered.
> Calling ioctl() to re-read partition table.
> Syncing disks.
>
> [RESCUE] root@vps-8b56af31:~ $ resize2fs /dev/sdb1
> resize2fs 1.44.5 (15-Dec-2018)
> The filesystem is already 10485504 (4k) blocks long. Nothing to do!
>
> [RESCUE] root@vps-8b56af31:~ $ mount /dev/sdb1 /mnt
> [RESCUE] root@vps-8b56af31:~ $ df -h
> Filesystem Size Used Avail Use% Mounted on
> udev 1.9G 0 1.9G 0% /dev
> tmpfs 386M 5.3M 380M 2% /run
> /dev/sda1 2.4G 1.6G 629M 73% /
> tmpfs 1.9G 0 1.9G 0% /dev/shm
> tmpfs 5.0M 0 5.0M 0% /run/lock
> tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
> /dev/sdb1 40G 34G 3.8G 91% /mnt
> [RESCUE] root@vps-8b56af31:~ $