What if one is unable to pay S$100 at once for 1777 call?

Last month, there was an incident and I had to call for an ambulance.

Remembering the advice from the Singapore Civil Defence Force to call the non-emergency ambulance number (1777) to free up the emergency ambulances for emergencies, I did so.

However, I was informed that there is a charge of more than S$100 for the service and it had to be paid in cash.

I do understand that 1777 is served by private companies. However, to get members of the public to dial 1777 instead of 995, there has to be a better way of doing things.

What if one is unable to pay cash immediately, but is in need of help?