Quality of Continental tyres bought at Tiger wheel.

I bought Continental tyres from Tiger wheel. I have not even done 25000km on the tyres (the car does not even do 5000km a year and drives around the suburb and not much further) and they need to be replaced, otherwise I do not get my multipoint check approved for Discovery. When I queried why the tyres (2 back tyres) were so worn I was told it was because I never have my tyres regularly aligned. If it were to be an alignment problem, I would expect the tyres to be worn down differently, which is not the case. In fact the front tyres are fine. As a minimum I would have thought Tiger wheel would agree to have the tyres checked, to understand why they had worn down so quickly. My expectation is that the tyres should last for at least 50 000km. ie double the distance. Vey dissappointing