Managed to move my last inherited customer away from tso before this started affecting things seriously.
I rate them about as high as Heart Internet, both seem completely out of their depths.
I moved two sites onto SiteGround as a test last year and had zero problems, support staff are technically capable and respond quickly.
Also free SSL with Lets Encrypt. Only a wordpress site but handles a decent amount of traffic and the dashboard is always snappy.
Compared to tso where load times for the same code were +10s