Rip off merchants!

I sent off my iPhone 4 to Mobile Phone Xchange after being quoted over £130. Like so many before they then said Imy phone was damaged and offered me an insulting £29! Unhappy with this I asked for my phone back only to be told they'd dispatched my phone in error so I could either accept £29 or they'd send me a faulty handset! Outraged I contacted the CEO of Vodafone as this was arranged through Vodafone BUYBACK. Someone called me & agreed I'd been treated poorly as I'd pointed out my bills showed I'd used my phone continuously till it was sent off therefore was NOT faulty and they compensated me £100 on the understanding I'd receive the other £29 from MPX. I emailed MPX yet they blatantly ignored me, not once or twice but 3 times! Eventually I called & spoke to someone who said I hadn't agreed to the sale - funny that rule only applies re the money transfer & not the unagreed dispatch of my phone! Anyway I've reported this to citizens advice and trading standards as I'm appealed at the similar stories I've found online! I should also add I left my story on their Facebook page & they simply deleted it - professional till the end!