as stated earlier by others, XML is not a programming language its like HTML a markup language.
what best you can do is break up the code in to two parts, part1 reading the configuration xml
and part2 processing the xml.
so the place where you are taking the user inputs can be converted to configuration xml like below
<transaction type="" />
<fastcash amount="" />
<balanceinquiry receipt="" pincode="" />
<fundtransdfer amount="" toaccount="" />
so this becomes your input XML from user, and then rest processing remains the same.
so just parse the inputs from the xml and then do rest of the operations.
Like if user sets value as 1, then readonly values present in tag fastcash and do the processing.