Bad service

Pnp asap customer service is the worst 😫 I ordered groceries yesterday and some items were not available and aske the delivery guy of how I will get my refund, he said they'll refund me automatically i don't have to contact them, i waited until i decided to write them an email, no response even today in the morning i wrote them an email and they're not getting back to me. What must i do now because calling them is going to cost me more and might not get assistance...so sad cause i almost liked this app👎