Lost control of NAS (F5-221)

[pbrain]

I mostly leave my NAS boxes off when not in use...occassionally I might leave them on for a few days or a week. Last week I started them up to store some new music files.
I opened both NAS's and create a folder on my F4-220 and tried to copy it to the F5-221 and it was refused. Turns out all my folders on the F5 are now 'Read Only' and i'm unable to restore this.
I've got access to the TOS system and can't find any way of getting my admin rights back. I have noticed in the user list, another user 'tttt' and i'm unable to delete it. Everything I try, it comes up 'unable to make changes, (file) is read only.'
I'm a noob to these things, these boxes have served me well for a few years and now i'm worried that my files are going to be encrypted anytime soon (if not already)...i've just switched them off for now.
They're running TOS 4.x

[TMSupport]

Unable to install any applications, unable to transfer any data to the NAS, unable to create or modify files or directories, prompt "read only", "cannot write", "no write permission", and judged as a read-only file system, something goes wrong with your file system.
Please back up data, delete volumes and storage pools, and recreate new storage pools and volumes.

[pbrain]

So i've got to buy ANOTHER NAS or DAS + 5x 8TB of hard-drives to back-up to? Great, just another £1,500+ and many long days of copying.

[TMSupport]

If you have enough storage space on your F4-220, you can back up data from the F5-221 to the F4-220.
Then delete the volumes and storage pools on the F5-221 and create them again.