On a modern nokia for example you can copy the wav to the phone and then set that as the ringtone.
It would just repeat for the seven seconds. You could edit or cross fade out and in using some free audio editing software such as audacity. This might make it sound more professional .
Thanks Dredwerker. It's an old (16 months) Motorola V3 but it has struck me that I'll get a new phone with my new contract in a couple of months so maybe it's best to live with as at present and go through the hoops with the new one.