I ordered a Canon telephoto zoom lens from this online store 5 days ago - its price was very competitive, hence why I'd chosen this store in the first place. The following day they called me to see if I was interested in buying a Sigma lens instead - only been on the market 2 months, they informed me it is superior to the original I had ordered, & the same price, $569. Long story short, I said yes. My lens arrived last night - I just happened to do some online searches about it & discovered that the majority of places online are selling it for $350-400. A substantial difference in cost. Now I can't get through to them (of course) by phone to see if they are willing to do a deal with me or if I need to return my lens to them (they'll charge me 10%) and rebuy it elsewhere.

If I have to return it, what are my chances of getting them to not charge me the 10% return fee? Is it worth me asking if they'll match the price at other sites?