help with a late payer

Hi, this is the first time I have used this board.

I have a commercial cleaning company which will be 3 months old on Wednesday. I am obviously new to business and a bit "green".

I have had real problems on one contract. The guy sacked me without giving the statutory 1 month notice and now will not pay his May invoice until July. This is for cleaning services from 1-31 May inclusive. The invoice was dated 1st May and should have been paid prior to May 15.

My T&C's state the following in regard to late payments



5 LATE PAYMENT
If the Client fails to make any payment the Company may terminate the Contract or suspend any Services. We will charge the Client an initial Late Payment Charge of £10 followed by the interest from the due date to the amount of actual payment. This will be at a rate of 3% per annum greater than the bank base rate. Interest accrues on a daily basis. If the Company takes legal action against the Client for breach of Contract, the Client will have to pay all fees, expenses and disbursements occurred on a full indemnity basis.


Should I charge him interest from the 15th May or from 30 days after the last date of cleaning which would be the 30th June?

Do you think my late payment conditions are OK? I think perhaps the penalties should be larger?

Please help me sort this out.