Told to wait 3 months before i can open a contract

I have been an MTN contract holder since 2006. My recent contract expired on 19 Dec 2014. I was going to be out of the country for the whole of January 2015, so I moved my number to prepaid on 2 Jan 2015. When I returned, I opted to take out a new contract at Kenilworth - I received an SMS (on 2 Feb) that I could renew. I app**** on 3 Feb and was told on 4 Feb that none of my details were on the system. I went to the Waterfront branch on 5 Feb to open a new contract, including having all my bank statements, salary slip, proof of address and ID just in case it was needed, only to be told that I cannot take out a contract and keep my same number, instead I have to wait 3 months before I can take out a new contract. I was told that the reason was because I cancelled my contract and moved to prepaid - even tho my contract had expired the month before!?! The sales assistant couldn't provide answers as to why that is the case. Ironically, I can immediately go to any other cellular service provider and immediately port my number and take out a contract. Other service providers even offered me a temporary number during the porting process - another thing MTN can't do. Really pathetic