HARRASSING CALLS FROM MBD

My STD bank Credit card was handed over to them in July- I did contact them and make arrangements. I do keep my promise that the account will be paid end of each month I did make a payment end of July. I asked them so many times not to phone me rather send an email as Im working in an openplan office and cannot just go out take the call. However it is so bad now that I have to put my phone on silent mode because I received calls from them not once or twice a day but sometimes up to 6 calls . I`m going to get into trouble and then Im without work. Who is going to pay my accounts then? I do understand that they will phone you if you do not pay - but why are you phoning everyday and 5x times. Nothing will change in a day. I asked for banking details but they said I must pay directly to Standard bank but my card is blocked and I cannot add it- I cannot go to a branch and now it is costly to phone the bank to make internal transfers.