After being with O2 for 9 years, since I was 19. They have marked a default payment on my credit score for a measly £7.50. I have had a perfect credit score until this date. The situation had arisen when my mums contract, which is paid for by me, had ended and was moved to EE. Usually I get prompted by the O2 app or by text however it seems once an account is closed, the number is no longer assocaited with the account. This leaves any outstanding amount to go unoticed and I have found this has happened to multiple customers from a quick google search. The outstanding balance sat there for 8 months until I rang O2 asking why I had two O2 accounts under my credit report. They were unable to explain why I would have 2 accounts until I suggested it could be associated with my mums previous accout. They never texted, emailed or sent a letter to any of the available contact options they had. When questioned why I had not been contacted the support rep was unable to provide an answer. I requested for the default payment to be removed from my credit score however the rep said it was not possible even though I had seen it was from looking online. I then asked for a manager to call me back and was told they would call within 4 hours but this obviously never happened. Their unwillingness to help after leaving my credit score tainted with a mark that lasts 6 years prompted me to reach out to TransUnion directly to resolve the issue. I am lucky I was approved for a mortgage just before this situation otherwise O2 would have ruined an opportunity for me over £7.50. My conclusion about O2 overall is no matter how much loyalty you show to a company they couldn't give two sh*ts about you and their reps would rather say they can't resolve an issue than to go that extra step for their customers.