started off good but now i feel its a waste of time

Looking back at my shell history I received 1 amazon £25 gift card over a year ago

I expected to get my second 1 around 6 months ago but as I got close it not only increased to £50 as the minimum amazon reward but the number of shells needed then increased by around 180 which I was not impressed with but thought a £50 payout will be nice. As I got to something like 20 shells away from getting my £50 amazon gift card I noticed the £50 option had been replaced by £100 and at that point I started to lose interest but thought it will come back (2 months on it has not and I doubt it will based on the replies on here). Why keep going for another year when they could just remove Amazon as an option completely or push it up to a £200 gift card?. no sorry I've had nothing from you for over a year and I lost all interest in continuing. I started to delete the email notifications and just did the odd 1 so I could check the rewards on the site which seem to be getting worse and worse including the selection of gift cards so tonight reluctantly I've cashed in all my shells for £50 of iTunes vouchers which I don't want but faced with that or anything else on the site its better than nothing which I think would be the case if I carry on hoping for a smaller Amazon voucher to come back and if they do well done to those who held out but I was not prepared to get nothing for my years time and effort if they were to close down