A complete waste of time

I have had a Sparks card since the very beginning and enjoyed the offers that came and it encouraged me to go into the store. Then I started not getting any offers whatsoever for over a year and a half or more. I spoke to a supervisor in the store and she stated my card was not working yet my purchases were an on line receipt.. I rang the call centre which is in Cape Town and the very polite people there are as much use as a chocolate fire guard.. They promise to sort it but nothing happens. Whe you email you get a generic email stating that sparks offers come from what you buy and are personalised and look out for offers. I decided to get another card on another email address and you get a £5 voucher off a £40 shop as a kick off then you get nothing even after many M&S shops and using your card each time. I really don't know what to do now.. I think dont bother but why should some people get offers and others none. A cashier at my store told me this is happening to alot of customers.