Capt Marble,
I use Onetel frequently. They ARE currently acknowledging several problems on their service, but I got my overnight Emails with no problem at all.
Never had any major problem with access, internet response, or email. If occasionally get engaged, I just switch to alternate access number, and get through first time. Make sure that you have identified your "best" access number.
Also use them for domestic phone, and make full use of their "free calls" option. Am thinking of switching to their mobile phone offer at £4.99/month.