MTN blocked my account because they "forgot" to change card details.

I called MTN as i have a new card, they took all my new card details and told me they have changed the payment card. I have a Reference number :***. Due to mtn's pathetic service, the card wasn't changed and now my account is blocked. Trying calling customer care 3 times, i hold for a long time and it just gets cut off. Pathetic service. Thats why they losing so many customers.