Got an offer to change a PDX-SEA-PHX to a later flight that day for $25 - which I accepted, then got another offer to change that 2nd flight to a later connection for (what I thought) was another $25 ... When I went to redeem the voucher, it was only $25 total. I ended up cancelling the flight, but was a bit miffed I thought I'd get $50 for two $25 offers but only ended up as $25 total.