Reward amount of coins increased without notice!!

Hi, I joined Cashwalk hoping I could get my first reward with3750 coins. I've just reach it and now to get a £5 voucher it shows that I need 6250 coins. This is not a fair deal. There was even not a warning to notify of the change. If I knew I would have tried to cash in coins quicker or would not have joined this app at all. And not to mention that if you forget to redeem the coins before midnight you lose them. This is a rip off, not worth it!!