Sell by date wrong

On Saturday 2016/04/09 I purchased 8 piece pnp free range chicken. The sell by date stated 2016/04/14, so i just put it into the fridge, with the intention of cooking it within the next 3 days. I took out 2 breast pieces on Monday 11/04/2016 and was intending to cook the remaining 6 pieces today Tuesday 12/04/2016. The chicken has gone completely off after being within the fridge for this entire period. I would understood if i had frozen and defrosted the chicken continually but non of that happened. It was in the fridge and in not even 3days it is off and 2 days before sell by date. I am not a happy customer. I am also not a big fan of waiting on the line not being given any indication of how long i will have to wait for a consultant, you guys must prepare the consumer that this is an estimated time he/she would wait before being assisted. after waiting 10mins i dropped the phone and decided to follow this root. I am so disappointed as i have been a faithful PNP shopper.