In spite of having boarding passes checked several times before flying, which were clearly printed to Seville, they were allowed to board the wrong plane.
The first they knew of the mistake was after arriving in the Ionian Sea and their phone networks switched over.
"Our phones were saying 'Welcome to Greece' and then our taxi driver said 'this isn't Spain,'" Humaira told the Mirror.
Allegedly the delayed service to Zakynthos had not announced its destination due to its late departure.
Confronting the Ryanair staff in the Greek airport, the Shaikhs said they had been laughed at, in spite of their tickets being clearly marked for 'Seville'.
Humaira and Farooq Shaikh were offered a night's accommodation and a flight back to London, although the next available flight was not for four days.
"They would only pay for one night's accommodation, so we had to pay for another three."
The pair, who had been packed for a hiking holiday around Valencia, were not prepared to be stuck on a Greek Island.
The trip was a gift from their son, Suleman, who was "outraged" by his parents' treatment.
He was able to contact them and rearrange flights and a hotel, however he was unable to get refunds on the lost nights and a bus tour in Spain.
The experience left him $2,118 out of pocket and with many unanswered questions.
"Not only is this a complete lack of safety, security and responsibility, but it has triggered severe strain and anxiety on my parents," Suleman told the Mirror.
In a statement on the incident a Ryanair spokesperson said:
"It is each customer's responsibility to ensure they board the correct aircraft.
"As these passengers passed through security control pre-boarding there was no security risk. We are working with our handling agents in London Stansted to ensure that this error doesn't reoccur."
The airline said it would not be refunding their tickets, saying the boarding gates and luggage check were properly signed for their final destination, and it was up to the travellers to board the correct flight.
"It is the responsibility of every passenger to ensure that they follow the correct procedures and take note of the information available to them."