Bank has kept my graduate account for longer than 3 years

Oren

While doing a little bit of account management today in online banking, I noticed that my current account is still a higher education account, which provides a fee free arranged overdraft. This account is only meant to last for 3 years, but it's lasted for nearly 6.
I often use my arranged overdraft (though I'm going to be paying it off soon) and I figure over the last 3 extra years I've used this account, I probably owe the bank a fair amount in overdraft fees.
My question is, if I inform the bank that I no longer meet the criteria for the higher education account, and if they then realise my account wasn't switched to a standard current account when it should have been, can they charge me for overdraft fees retrospectively?

I can't find out any information about this from their website. It just says that after 3 years, you'll be moved to another current account. That appears to suggest that it's automated and I don't have to inform them myself (I mean, why would the onus be on me to inform them that 3 years have passed??) 

Anyone have any experience or advice in this? Much appreciated! 

SDMN2020

Normally student accounts have a fixed term of 0% interest. So if the account was for 3 years I think in total you get 4 years no interest. Could you let us know what account it is and who it is with.

Thrugelmir

Most likely the bank simply hasn't got round to implementing the change. Other issues have been prioritised first. 

Oren

Thank you, the account is with Barclays and it's a Higher Education account