No care in the world

It’s difficult to comprehend how business get away with making rules that customers are forced to follow but fail to action a request from a customer when those rules are followed and obeyed. I was given a settlement amount to settle by the 7th January (a Sunday imagine) asked for banking details and was never provided with these. Any way I ended up settling the account via paygate on the 6th and I have been begging for the settlement letter to be send to me and I am told I will get the letter 7days after payment, why? I mean there is no one a customer can reverse a paygate payment why can I not be send the letter? I was terrorized by your call center agent even though I had get to the agreement of paying every month. I was called, sent sms and they had the audacity to tell me they will continue doing this until I pay. I have paid why cannt I be sent the letter and released from these shackles.