Prokard Membership and Voucher Usage

I have on many separate occasions in the last 2 years tried to use my Prokard Vouchers. Every time there seems to be an issue<br> The latest one being on Dec21 2015, I called and checked in at Protea Knysna, only to be told I can not use the voucher,(Voucher= stay one free night, pay the second or second and more nights of your stay) the hotel had space but wouldn't allow me to redeem the voucher, what is the purpose of these vouchers if there is always some clause that hinders the use thereof. The fact that we are members should allow us, as loyal customers to claim benefit if space permits. You can not say your allocation of vouchers is full for the hotel and normal stay is only allowed.<br> I did try calling central reservations to fix up but the office was initially closed to assist, then only to be told the following day that they can not assist in this matter. <br> Where is the loyalty with Protea Hotels, is this just a **** to get us here and then we at your mercy. Apart from the 3 separate poor instances of dab service I have encountered first hand, there have been other times where I simply just booked elsewhere due to the poor service or differing rates from Protea