He said prior to the incidents last week, it hadn't happened for a while.
"Last year in May it happened four times in one month.
"Since then we have been keeping a closer eye on the forecourt so it did die down, but it's started up again."
After the thefts last year, the couple introduced a system where people had to pay for petrol before using the pump.
But this had become a "hassle", with Mrs Patel saying it had been confusing for her and her husband to keep track of things when they were busy.
She said it had also been confusing for customers, especially for some of the older ones for whom pre-paying for petrol was an unfamiliar concept.
Mrs Patel said if someone wanted to fill their tank they had to pay a deposit, fill their tank and then pay a second time to make up the difference, which was "frustrating" for everyone.
Because none of the other service stations in Wairarapa used the pre-pay systems full-time, the couple abandoned it in fear it was putting off their customers.
Yet after last week's incidents, involving one person driving away with $70 of unpaid-for petrol in their vehicle, and the other with $117 worth, they have reintroduced the system.
However, it is only implemented in the early morning and again after 6pm.
Mrs Patel said it was more likely people would try to take off without paying if it was dark, and the system would be less of a nuisance at times when the service station was quiet.
Last year the Patels reported the thefts to the police, who arrested some of the offenders.
"They put them in court and the court said they had to pay the money back," Mr Patel said.
"But we haven't got any money back - not even one single dollar."
He said this was a common issue for all petrol stations.
"I didn't complain last time because it's wasting my time and the police's time."
