Disappointing! Online Shop incorrect size delivery

I placed an order for the Queen fullfit fleece on 19th June. An error occurred on the page when payment went through therefore it never reflected on Momentum's side. After sending my bank statement and after numerous correspondence my Electric blanket was delivered on 8th July. I was rushing to Mpumalanga and never got a chance to open my Queen fullfit fleece. I opened it today and to my disappointment a double fullfit fleece was delivered instead of a queen. After waiting almost three weeks for my order - the wrong size is delivered! Please response asap as to how this situation will be rectified. Poor service!