Paying a fine or interest?

Today I came to pay the toll for Highway 6 Crossing North.
 
One of the invoices stated

"The invoice contains a special charge for non-payment"
 
I probably paid late and then there's a section that says this:
"Collection fee for unregistered customer" 1.37 NIS
When I called them to ask if they had a business permit and if it was interest, they told me it was a type of fine, not interest.
 
They didn't give me a satisfactory answer as to whether they have a business permit or not. I searched on Google and couldn't find a clear answer.
 
Regarding payment
 
I checked in this morning and paid for it.
"Collection fee for unregistered customer" 1.37 NIS
 
Could it be that I paid interest and thus violated the interest prohibition or is this a penalty for paying on time?
The truth is that their sections are not clear.