Damsons deformed
 

I have a 5 year old merryweather damson tree. Last year it suffered from leaf curl on parts, but mostly on the top, which I put down to a very wet spring and summer. The fruit was fine.
I treated the tree when it became dormant with a winter wash. I used the EEC regulation product.
However, this year the leaves have curled again, but some of the fruit has grown split and deformed like small bananas (picture attached)
Please can you recommend how to treat it?