Jetstar horrible rude at Singapore.

13 july we have a flight to Singapore with Lufthansa.
From Singapore to Kuala Lumpur Lufthansa booked us wit Jetstar Asia.
The gate from jetstar was in a different terminal and a long walk .
We just made it on time but not get a ticket from this flight and online checkin was not possible.
But at the gate 35 min before the flight the transfer desk refused a check in.
Claiming it was 30 min before departure and the systeem did not allow a check in.
She send us back to Lufthansa a20 min walk again.
No problem for Lufthansa we did get a flight 1,5 hour later.
Back at Jetstar they refused to check us in again Claiming Lufthansa did not paid this ticket.
And the tickets where very expensive 700 euro they want.
Our Total Ticket was 600 and for one hour they want very much money.
Send us back to Lufthansa again refusing to give Lufthansa a call.
Lufthansa tried to call Jet star and they hang up three times.
Finale we did get a ticket for Silk air.
Four hours later we finally arrived in Kuala Lumpur.
I send a mail to Jetstar and did get a basic answer hopefully I will use Jetstar again.
And they will discuse the problem with the manager in asingapore.
For me never ever I will fly with Jetstar.
I used cheap flights like EasyJet and Air Asia en was satisfied.
But Jetstar is horrible and I hope Lufthansa will not use this company anymore.