Bad service from MTN

Could someone from MTN contact me my bill for June 2020 an July 2020 is billed incorrectly. Tried the 135 number nothing happens no option to speak to anyone at MTN. SEND an email got a reply on that you will contact me in 8 working days it's been more than 8 working days no call from you no sms from you NOTHING!! Your MTN Branch in the town was even worse your employee, behind the counter when ask about my faulty account just said"O sorry i dont know" So please assist in this issue!!