You are integrating a number of components into a single sketch which has now got quite complex and you are getting logic errors and it is difficult to follow.
It appears that you have got the LCD right because you get a message on it.
But your error description is focused on the logic to handle the coin acceptor. My suggestion is that you create a new sketch which handles only the coin acceptor logic (that is without LCD; Keypad, Relays etc.) and imbed lots of Serial.print statements so you see what it is doing.
Once that works, start adding the LCD and then other components.
I've also noticed this:
//bad pins to use as these are used for Serial
const int motor3 = 1; //relay in 3
const int motor4 = 0; //relay in 4
//unusual
int sell = (led1, HIGH);