No service assistance from MNT

I received an sms to upgrade. Went to the Kollenade store in Montana and spoke to one of the consultant who were very helpful. I especially asked if the were any upgrade fees payable and he assured met that there was only an R 110 fee to be paid with my next billing. My contract use to be R 480pm it would now go up to R519pm. Then I received a sms that an amount of R610 was immediately due for the apgrade as well as the monthly subscription of R519. I queried this and was given a reference no and told it would be investigated. On the 16th of October I went to the Kollenade store and again was give an reference no - it would be investigated ...... this morning I was grey listed for non payment. I phoned the Kollenade - explained to lady that assisted me on the phone what the problem was - she insisted that the upgrade fee was not paid and the dropped the line. I cannot get through on their 135 number - no feed back nothing!!!