Student Loan Overpayment

Vlouise7

Hi all -

Wondering if someone can help me - I recently received a letter off student loans saying as I had not responded to past letters (I've not had any) re: an overpayment they had made, I owe them £369 and debt collectors would now be in touch.

I've logged onto my student finance and looked through the letters and it has a log of 3 other letters which I've never got stating the same as the one I did get, and then has one from Jan 2020 titled Grant Overpayment Letter. Every time I have clicked to look at this letter, it's unavailable and says to try again in 24 hours. I've tried it everyday for the past two weeks.

My last year in uni when I recieved a grant was 2015, but as I can't get on the letter I can't see when its supposedly from and am weary of ringing as I don't want them to think I'm willing (or able) to pay this.

Is it normal for them to have taken this long to get in touch about an error on their end, and where do I stand with it? 

Apologies if I've posted in the wrong section but help/advice would be much appreciated!