Most companies get swamped by contractors calling them for business so it can be really hard to get buyers attention. You need to put your name in front of them as often as you can at the lowest cost. Could you create a top 100 target list of potential clients in your area and post them a letter every, say, 3 months. Sooner or later you'll catch them at the right time when they're looking to review things. If the letter costs £1 per time it'll cost £33 per month but if you kept it up over a period of 12 months you'll have a better chance of getting called when the do want to look at it.
Regards
Mike
