How do I make provision for an oversize item?

[trad51]

Post office largest size appears to be Medium parcel Up to 61 x 46 x 46 cm but my item will be slightly larger than that. How do I choose a mailing method?

[**peaseblossom**]

The opt-out of Simple Delivery for large items isn't working properly at the moment but see the workaround solution on here:
https://community.ebay.co.uk/t5/Seller-Central/how-do-you-list-anything-bigger-than-61cm/m-p/7882486...