Disappointing service

I have a contract with CELL C. I noticed that I am unable to dial any number preceded with 0860. I notified CELL C about this. An agent from CELL C called me back and informed me that I am in fact not able to call numbers preceeded by 0860, I will need to purchase additional airtime to enable this. This is ridiculous, my contract presently allows me 60 minutes any net minutes, and 120 on net minutes. Why should I have to purchase additional airtime to call numbers like this??? It is very very disappointing and I am considering changing service providers.