Piggy Riches Megaways is a terrible one for me as well. Ive been playing the freerolls at videoslots the last month and I had the bonus once yesterday and it paid absolute crap. I did have a bunch of Jacks in the freeroll that surprising were worth over $11 on the freeroll .10 bet which with no multiplier was very surprising.
Sadly for me its just been a tease everytime, and the wild multipliers have never connected to do anything useful. I also played it with real money and never even managed the bonus or a decent win to keep spinning. I like the style of game but theres better paying options for me .