Vodacom Dual Sim Dilemma

Hi, I had been using a Vodacom prepaid sim for a couple of years now on a single sim card phone with no problems in terms on internet connectivity. The problem started when I got a new contract dual sim phone with Telkom. I started to realise that when I'm using my Vodacom data on this dual sim phone, the video downloads where not good as they had scratches and the sound was also disrupted as it switched off on some. I then tried downloading the very same content video from the same websites but with a Telkom sim data, to my surprise, the video came out clear and the sound perfect. upon suspecting that maybe the problem was the old Vodacom sim and the Telkom sim was new, I then did a sim swap on my Vodacom prepaid sim card. Unfortunately that didn't help as I was still experiencing the same problem. I then tried to reset my sim and networking settings after backing up my phone but that didn't help either. The thing is now the Vodacom sim didn't want to accept the internet settings as it said the settings were invalid. Honestly speaking and oddly, the Vodacom sim still connected to the internet fine and the speed was ok but the videos and sound quality was no good. My frustration led me to consult Vodacom customer care and I have to admit I was sceptical as I honestly believed that this have to be unique. My suspicions where proven right as I was continuously assured that it must be the websites I'm downloading from even though I clearly stated that when I do the same with a sim from a different network I had no such problems. I guess the mention of the efficiency of a different network obviously did me no favour. After being taken from pillar to post by the *********** Vodacom call center they finally referred to me to Vodacom tech center. Upon my arrival there at the Eastgate Mall I guess I should have gotten the hint from the question I was greeted with of where I got my dual sim phone from. To cut a long story short that technician allegedly tried something and assured me that it should be fine after that. Upon realising the obvious I then went back and then referred to a different agent. Again I wasn't helped and I was then advised by those guys there at Eastgate Mall Vodacom Tech Center to go to the Telkom Store as they suspected that there must be something wrong with the phone. Out of desperation I went. Thing is, I really preferred the Vodacom data deals for my data downloads and I was really frustrated. At the Telkom store I was enlightened to something that I feel should have saved me my time and money by anyone of the Vodacom employees as surely they knew. I was informed that this problem was not unique to me. Vodacom doesn't normally issue dual sim contract phone and in the event that they do, they disable the other sim slot. I was then informed that the Vodacom sim doesn't work well on dual sim phones more especially of other networks. So why did I have to learn from employees of a competing network about a problem of Vodacom. I do feel that that information should have been fed to me by the very first person at Vodacom. As to my problem......not resolved as was advised to use a single sim phone. So now I have to carry two phones because Vodacom doesn't want to compete with anyone I guess.