Online retailers failing to honour warranty


I am hoping one of you can help.
Expansys - failing to honour warranty.
I have had a problem with my HTC OneX phone and expansys fail to honour warranty. Expansys do not reply to emails, phone calls or call you back when they say they will. They basically seem to mess you around for months and then tell you that your warranty has expired as they only offer 3 months, even though they clearly tell you it's the full manufacturer warranty before you purchase. Now they tell me that they just changed their warranty to 12 months a few weeks ago, but as I purchased before that, I'm out of luck.

Any Ideas? perhaps generate some public pressure for them to make good on a promise?
My health is not too good these days as I have some serious issues, and this is the last thing I need..... I would have thought the internet would be something that would help me, not make things worse...
I could send the phone back to HTC, but then there is a heap of problems with that as HTC Australia will say its not their phone etc etc... and anyway, that's not the point... Expansys should be held accountable...
I look forward to hearing from you. Warmly, Marty