I have had awful problems with this too. I currently have nearly £3,000 due in for this term and almost a thousand from a selection of previous delinquent payers.
Does anyone else find it really hard and embarassing to phone and chase? I just can't do it. I send repeated letters through the post but even that doesn't always work. I did buy some red stickers which said "your remittance would be appreciated". I stuck them to reminders and it certainly got a few to stump up quite quickly.
I have very prescriptive T's and C's which state no lessons after week 3 if payment hasn't been made. BUT they don't seem to work. This is probably my fault as the pupils keeps turning up and I can't bring myself to send them away. I did once and it did work although the mother wrote me a very stroppy note along with the cheque! She owed the previous term and it was half way through the next term What a cheek!
I feel it's unfair on the pupil as it isn't their fault!
Anyway I joined musicteachershelper in August and this has improved things enormously. I cannot recommend it enough. I can send out repeat email invoices as often as I think appropriate. I find that doing it weekly is getting results. The amount owing is reducing quite a lot each week. I have 80 pupils on a one to one basis at the moment and the admin is horrific. This site has revolutionised my life! I am able to say to parents that the repeat invoices are sent automatically until payment is recorded in the system! That way they don't get cross with me bombarding them with invoices!
Interestingly, most of the parents love the site too. It also allows the pupils to reschedule lessons on the online booking service. This helps with the perennial problem of missed lessons and will the parents pay. Mine are told to go to my online calendar and choose from a selection of free slots and book a replacement. if they don't they have to pay for the missed lesson.
I am afraid to say that in our line of business, whatever we do it will always be a bit of a problem. For some reason parents think of it as a pocket money occupation. Probably due to the old stereotype of an elderly lady teaching the piano to supplement her pension!