Unacceptable!!!

Last month I received an invoice for an amount that is 5 times the amount what I normally pay a month. I went into Mtn Summit Road (21 Apr 2015) and spoke to Amanda. She said that I needed to come back into the store 3 days later (24 Apr 2015) to lodge a dispute on the account. She gave me her cell number and asked me to call her on Tues 28 Apr for an update. I tried to call her 3 times that day and left messages, then again on Wed 29 Apr and Thurs 30 Apr and still NO response. I went back into the store (now my 3 trip there) and when I asked her why she hadnt responded to all my calls, she said it was because she didnt have an answer for me. I explained to her that ignoring my calls instead of communicating that with me just annoys me! She assured me that she will get back to me as soon as possible and that I must not worry. Days passed and still nothing so I sent Amanda a text msg on 11 May requesting an update but again NO response. I tried calling a few more times but again nothing!! Today Monday 25 May I called Amanda and she said there is a strike and put the phone down on me!!! I called the Mtn call centre and could not make a complaint due to the strike! Unacceptable!