Lots of members are unhappy about Simple Delivery.
If you want to keep selling on the site, where you seem to currently be selling very successfully, you may have to adapt and consider your options.
If your hobby? of collecting and selling clocks has become a business, you could upgrade to a business account. Simple Delivery is not mandatory for business sellers.
You could opt to use Royal Mail only and have your parcels collected by Royal Mail.
You could pay a reliable person to post your parcels once a week.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)