Wrong Rates Appearing

[Deoctor]

Hi

 I have been trying to create a shopping cart builder, i am using PHP and Javascript. but i need to pass three values through ajax, Could some one kindly help. 

index.php

getvehicledata.php

getdiesel.php

getrent.php

[ginerjm]

I don't read external files, so my purpose in answering is to ask if you have made the effort to add some debugging info to your modules to be sure that what you expect to happen is actually happening as the flow passes thru each module.  A few echo's can go a long way towards isolating your problem so that THEN you can post the offending (small) section of code and perhaps get a quicker answer.