In April, my Xbox Live subscription was up for renewal but unfortunately Microsoft is unable to charge my credit card (which is no longer valid). I have attempted to change my payment method to another new credit card but the transaction was somehow not approved (i.e. the credit card details cannot be changed). I believe it is because I am using a Malaysian credit card but the address details included is Singapore.

Thereafter I tried calling Xbox Singapore but was unable due to the SG toll free number which cannot be called from MY. In view of this, I got a friend of mine in Singapore to call the toll free number (impersonating me!) and asked them to remove my credit card details so that I can then use prepaid card to pay for the subscription. Apparently my friend (after calling them) was told that they can cancel my previous credit card details for next year but cannot be backdated to this current renewal as the renewal has already been made but unfortunately they cannot charge to my credit card.

Sorry for the long story but I have the following questions which I hope someone will be able to help:
1. If the previous credit card details are still in my Xbox account, can I utilise a prepaid card and pay for this renewal? 
2. Did anyone experience the same problem whereby you cannot change credit card details? Am I correct to put the country as Singapore and not Malaysia in the address line? 
3. Does anyone have any other suggestions? I really hate to have my account suspended and cannot be activated again and hence lose all my gamer points and history. 

I really appreciate if anyone out there who had similar experience as me and got the problem solved can guide me on what needs to be done.

Thanks!