Horrible service the last two months

I have not had problems until recently. The previous month my payment was debited and it wasn't picked up by their system until two days later and they already blocked my phone. The last 4 weeks I have tried to change my banking details with them. Empty promises of returning phone calls. The online payment system does not work and basically no assistance in changing my banking details for four weeks. Now my devices has been blocked again and there is no assistance on how to make a payment to unblock it. I am really frustrated with the situation and the contact person refuses to give their name so I can escalate the situation