Old mutual very unprofessional

Beware of old mutual I have received a shock of my life when they say I have unpaid premiums from 2021 what's surprising is that the whole of 2022 to 2024 they have been collecting premiums faithfully they could not pick this oversight which is clearly from them their side. Imagine if I had to claim and then they would tell me no you owe a premium of 2021 in 2024,I don't know if it's your systems or you just don't care about your clients I'm disappointed actually disgusted.