We bought Megan and Archie martingale combo collars from
http://www.collarways.co.uk about a year ago. They do a really good range of funky designs and colours, with matchign leads, and the quality is excellent. They have a no-quibble even-if-chewed gaurantee, and they've just demonstrated that they're as good as their word. I noticed the beginning of a very minor fray in Archie's collar where he pulls and the material rubs against the metal ring of the martingale, so I mailed them to ask whether everyday wear and tear was covered by the guarantee and they said 'yes - send it back and we'll replace it, and would you like a different pattern this time?'. I posted the old collar second class on Tuesday, and less than 48 hours later, a brand new one has just arrived. I can't recommend them highly enough - outstanding customer service!