Cancelled flight Easyjet - advise please

Hello, we were due to return from Mallorca to Bristol on Friday 13th (!!) - our flight was cancelled due to bad weather. (our flight was due to leave at 2pm but the airport had reopened its runways by 11am and it was blue sky. so not sure why we were cancelled rather than delayed)

But Anyway.... We stood in a queue for 4 hours to see the customer service desk. When i reached the desk the earliest Easyjet flight they could get us back on was Tuesday 17th. Or Monday 16th (but into Gatwick) I found a different flight with TUI for the Saturday but returning into East Midlands instead. We needed to get back as my son had missed his Grammer Entrance exam as a result of the cancellation and needed to get back for him to book his resit. The customer service adviser told us it was fine to book with another airline and we could reclaim the cost of the flight in full through the expenses section of the easyjet site. I questioned her twice to be sure and she confirmed.

I therefore paid almost £600 for new flights to EMA the following day. In the meantime, Easyjet put us up in a hotel for the night.

Upon submitting my expenses claims, it seems that Easyjet are refusing to pay for our flight as it was not back to our FINAL destination (i.e Bristol). I am so angry because we could never afford to have spent this if we thought we wouldn't get it back!

We had no other option. There were no other flights in to Bristol and Easyjet couldn't get us back for 4 days! Our options were Gatwick or East Midlands. So we went for East Midlands as its closer to our home.

Where do i stand on this????