We have an unwritten policy of helping customers who call with a problem with hardware they did not purchase from us. Call traffic permitting, we try and provide first level help without cost – evn though our formal policy is that we will charge for any call relating to hardware not purchased form us.
In most cases our approach is appreciated by our customers – we can usually help them resoolve an issue without having to hunt down a local hardware supplier.
Where we do draw the line is the regular calls from people about hardware we did not supply. A couple of customers abuse our generosity to the point where we may review the unwritten policy.