Ikea Hyllestad Topper Damaged and replacement?

I have an Ikea Hyllestad 90cm x 200cm sized mattress.

Unfortunately one of my children had an accident on it and although we had a mattress cover fitted it went straight through and badly soiled the mattress.

Although it says do not wash I have tried washing on a cool wash followed by air drying. Unfortunately, it has shrunk and seems impossible to get back on. Do you know of any manufacturers who could supply a suitable replacement?

I tried IKEA and they couldn't help.