R3 999.00 Booster Seat not Safe for Children

I purchased a Chico booster seat from Baby City Benmore on 27 December 2017. I asked for the safest, most reliable booster seat for my child and I opted to purchase the most expensive one believing I was getting all that I had asked for. Nowhere was it mentioned to me that the polystyrene was easily accessible to my child. I have a 4 year old child that has been chewing the polystyrene by merely lifting the cloth and this is extremely hazardous to any child. I brought this to the attention of Baby City and they have asked me to bring in the seat. I was later advised by Baby City that there is nothing that they or the supplier can do because it is not a factory fault. I paid R3 999.00 for this booster seat and I am left with a seat which can no longer be used.