Vodacom poor Data internet service.

Since I stopped mostly contract and start pay as you go. I experience problems with internet reception, even if I am close to the vodacom towers. My wife who still have a contract has excellent data reception. I contacted Vodacom on 135 and was informed that I must rather use the *135# to purchase data. He refund me for the loss I had and when I purchased data from *135# it worked perfectly. It seems to be a problem any other way. I then reciently bought data from my Vodacom app. Same thing happened, I could not connect to internet. It seems to me Vodacom try force us on a monthly subscription. I am considering to move over to another Mobile Company.