Mtn unable to acknowledge proof of payment

2 weeks ago I settled my account with Mtn , I have been calling them to email me proof of payment letter and to confirm if the account is closed , their call centre agent they transferring from one person to another until they drop my call several times , even worse after I settled my account contract account they took the contact number and give it to someone else no acknowledgement of payment, service is very poor their agent they don't care about clients, I am not even sure if they are given training