Ok my nasty idea has been confirmed,although my earlier comments about the poor build quality of clone 500's still stands.
Im pretty sure you have bought a receiver which connects with a commercial (pay) card share server. Now forum rules state we cannot discuss problems with pay servers because if we are seen to be promoting ways of evading subscriptions we could be closed down.
Therefore I shall give general guidance only.
Right any problems with channels freezing are the problem of your supplier. Freezing is a very common problem on pay servers as the providers connect far too many folks to one card leading to slow updates when the keys change which can be every 30 seconds at times.
You will find the old hands think pay servers are run by the scum of the earth due to multiple shady business practises which can be anything from links with organised crime, to leaching off other folks cards and resharing them.
If the provider gets busted your IP is in their server logs so dont be surprised if the old bill come knocking.
I hope you havent had any ahem guarantees about how long the service will last "guaranteed for a year" maybe?? Sky UK will be implementing some new anti card share protocols in the near future which will almost certainly disrupt the activities of the scum providing access to uk channels.
Basically you will have to contact your supplier to see if he can sort the problem out, but be aware your access to Sky UK could disappear at any time.