can someone give me some suggestion

I am in a factory which makes geared motor (ac motor).Recently ,I am facing one problom .About 7.10 ,I get one enquiry of geared motor from UK .After several emails ,the customer tell us that they need us to send two samples.m)rlV5L^9D;[PA
They have said they would pay for the freight .and he gave me theire TNT number ,while the sample he needed is on preparing ,we have just opened the new model for the type he needed .9JR~5c:P+o2S
  At first the product manager told me it just need 10 days ,while after more than one month ,the sample is still unprepared .thogh I have rushed them not only once .during the preparing time ,I have to once and once again told him ,there needs times to prepare the new products. and the customer seems not worry .he just told me ,when the sample is ready ,told him.
j5c9f%oI   until now there seems still needs at least one month .and for the Olympic ,the motor is not easy to be delivered ,for the motor contains magnetism. One express told me they can deliver it .And it can just be paid by us .and I told my customer to remit the money ,while he said that only he get the samle ,he will remit the money .I browse their web ,and i trust that they are a big company .and they won`t default the money .H|&~}c VO
  While now how should I explain to my customer ?

Revert the sample charges if he accept your samples & place order.

you can revert the sample fees.Because if you want to do this business success,you must do it as the customer want you to