The Tevion PVR's are identical to Technosonic ones (also sold by Aldi), Goodmans (sold by Argos and B&Q) and also Bush models sold by Tesco. They are all made by a company called Technosonic.
There are lots of discussions about them here
http://www.digitalspy.co.uk/forums/forumdisplay.php?f=90 where you will no doubt find your bugs mentioned.
There is a software update due in early December. Keep an eye on this page
http://www.dtg.org.uk/retailer/download_schedule.pl for updates to all types of digital terestrial receivers. you will see an update to your machine is due between 8th and 9th December.
Try updating the software first and see if it fixes the problem.
What most people seem to be doing is keeping the unit in the hope that software updates will fix the problems, safe in the knowledge that if not you can still take it back within a year for a refund.
Search the archives of that forum above, I am sure they published some technical support details.