Other networks cant get through to my number

Good morning <br> <br> I took out a contract last year August with Altech Autopage (Vodacom). <br> <br> Since last year, after numerous attempts to fix this, I am still not getting any sms's and phone calls from certain numbers. When they try phoning me it says my number doesn't exist or incorrect, I have wasted money by doing a sim swop and it still doesn't work? I have been missing very important phone calls due to no one that can assist me with this. <br> <br> Please will you assist me urgently with this problem. I am not sure if I will even be able to receive your call as people who are trying to call me from a landline also doesn't get through. Please email me if you cant get hold of me.