compensation offered, should I take it?

Hi everyone, I am a long time reader of the forums but this is my first time posting.

Virgin credit cards made an error on my 0% credit card and they were taking interest out of my payments when they shouldn’t have. I complained, they looked into it and now offering the following

all interest has been refunded and this will reduce my balance (this is already done).

To cover the period I was without funds they calculate compensation at 8% giving a figure of £78.56. They deduct 20% tax of this which is £15.71

On top of the above they are offering a one off payment of £25 as a gesture of goodwill. It does not state but I imagine they will tax this too?

Overall I will receive 103.56 less tax, so just over £80.

I am not a greedy person, but on the other hand I don’t want to let them get away with it too easily either.

I had a frankly awful customer service experience with their representative, the lady over the phone was not helpful at all, she showed no sympathy whatsoever, when I realized I was being overcharged several hundred pounds and called them to work find out why. She kept telling me that I made a late payment and so the promotional 0% rate has been removed and that was that.

So I just wanted to ask what everyone’s opinion is, should I just take what is offered and shut up, or do I take it to the FSCS / ombudsman to try and get a bit more compensation out of them.

TIA