I worked at the Zales you are talking about during that time. Your story doesn't add up to me...sorry.
First of all, the Diamond Bond (if the diamond chips, falls out, or cracks) is free. Second of all, if your fiance purchased a warranty for your ring (which would cover sizing, rhodium dipping, and prong work) there is NO WAY that your warranty was $280 - unless your ring costed around $15, 000.
Second of all, if you just took your ring in to be cleaned no one would tell you that your ring needed to be sent out and wouldn't be back for 6 weeks. If there were missing diamonds at that time, yes, it would need to be sent to the diamond bond center (the place that replaces cracked/missing/chipped diamonds) but if something was just loose it would have been sent to the local jeweler and back within the week - or less.
As the person above mentioned it is in your diamnd bond paperwork that you cannot get work done elsewhere.
I also find it hard to believe that one of the guys there laughed in your face and said "you're kidding, right?!" There were only two guys working there then and one was the manager who bent over backwards to make everyone happy and another guy who did the same.
There was an unwritten "rule" at that store, too. If someone had that many problems with a ring that was just purchased a new one was ordered because there should never be that many problems right off the bat with a ring.
Sorry if I sound like a complete [censor] but I worked there full time for quite a while. The manager made sure no one had a bad experience there and if you had been in several times and was unhappy he would have known about it and fixed it.