The one time my label printed out like that, I used whiteout over the 22kg and used the text thingy to write in the correct weight that I had paid for.     If you are using a B4 box you would have to be careful about whether is would have beeen cubed, in which you put the cubic weight i.e. 16 kg cubic - otherwise put 5kg.

My white-out parcel scanned okay at the PO and has been delivered, so I don't see a problem.   Surely they are working on this.

Luckily it doesn't affect the ebay satchels for 500g and 3kg.