That is just plain UNACCEPTABLE.
They have taken a free shot at you.
Would they have cancelled the bet had it lost?
At the very least they should have paid you at the correct odds.
I'd be lodging a complaint with their regulator over that.
Matchbook is certainly worth a look. Frequently appears to have more liquidity than Betfair for handicaps, although mostly they quote only one line.
And Pinnacle of course.
I have operated accounts at both SBO and 188. Both do offer competitive AH odds for football (soccer). For other sports they are not so competitive. However there is a big difference in the size of bets they will accept with SBO way out in front.
Further, based on my experience, 188 will reduce...