2001 Ford Expedition Front sway bar link bolts

On my 2001 Expedition, the front sway bar link bolts have begun to continually come off. I have replaced them 4 times with new ones which then come off after about a week. I drive roughly 19 miles a day between work and home. The roads I drive are old country roads which we in the US would look at as little more than large sidewalks and are very curvy and bumpy. Not many straight roads here.

I live in England where there are no shops which will work on this car so I have to do this myself. Also, I have to order the parts from the US.

Please help.

Adam