Have you got the 21" 7 spoke alloy wheels , as i only thought you could only have Dunlop SP Sports max on this wheel option ?I had exactly that problem and the alignment was done once at 7000 miles. I had two sets of tyres in 20,000 miles as they averaged a bit less than 10k each set.
However, after reading the forums and pumping up to 40psi to 42psi as a minimum and maximum and opting for budget Maxxis tyres instead of original Conti and then Pirelli, I find that the current set appears to be less than half worn at 10,000 miles. Result. And look at what I paid for them!