Replacement Spool and Line Performance Power Grass Trimmer?

Can anyone point me to a supplier for Replacement Spool and Line for a Performance Power Grass Trimmer Model PWR 550DGTA. I bought it from B & Q last summer, and have been
to several B & Q stores to source a replacement, but not one of them stock this item. The model has been updated this year, as have the Spool and Line holder.