Hi
I have no legal training but have on the ground school fees paid many times over.

As far as I know , small claims court will not take on a business claim - They will take a personal claim against a business but not the other way round.
I am assuming it is a builder type set up that you were working for/sub contracting to and the builder was getting the money from the client.

First step that we now use when the first payment is missed , Inform the builder that he has 3 days to rectify where after you intend going to the client.
3 Days later then inform the client that payment has not been forth coming and we need to suspend work or be paid directly .
If that does not have the desired result we then sent a lawyers letter demanding the monies owed and a threat of high court action ( +/- 10K ) - inform the client that he will be subpoenaed as a witness to verify payment.
To get an advocate involved and start issuing high court papers +/- 30K
To end up in High court with an urgent application +/- 60K

You have to be careful as once you start down the route it can become messy and unstoppable.Also be careful to start suing out of principle as the only people that score are the lawyers.

With the amounts you talking I would go step 1 and 2 - After which I would make sure that I have home telephone numbers.
Phone him on the cell at 2 in the morning which generally gets a reaction and then you are blocked.
Next morning phone the house phone.You may need to then stop a bit and start again in a week or 2.
Knocking on the door in the present SA at 2 in the morning can be dangerous.It used to work well.

They generally get upset that they were sleeping and you woke him up - My answer is that I could not sleep worrying about the outstanding money and how to pay suppliers.

Threaten to start removing equipment not paid for can also get a reaction but is illegal.I once starting taking out a 300Amp CB to a bakery because I got tired of being pushed around - Just a tool box in the sub station was sufficient to have a cash cheque shoved into my hands.
Cash Cheque if it bounces is fraud and you can take the bounced cheque str to the police station - In the old days the banks used to charge the person writing out the cheque if it bounced - We were owed R250.00 and managed to redeposit the cheque 4 times before he had funds.He was furious when the bank charges came to R350.00 - Now days , besides not really seeing cheques , the banks charge you as the depositor.

The ideas above are also dependent on what the contract says or order number that you received. I have pasted below a standard type demand that we use as step one.

RE: LATE PAYMENT

Contract - ????????????
Contract Document - ????

Further to our telephone discussion on Monday with regards to the late payment on the above contract and with reference to our appointment letter

We presently have 1 payment outstanding
Payment 1 - R ??? ex vat due 05/02/2017

There has been a breach of contract due to the non payment and we are left with no option but to exercise our rights under Clause ??? and issue 3 days notice, of suspension of works

We trust that you will realize the very negative effect which your failure to pay us timeously has had on our cash flow, *and our ability to meet the requirements of the programme. **We sincerely hope that you will now make urgent arrangements to honor your obligation towards our company.

Hope the above meets with your approval

Kind Regards