Problems with the modification an existing module

[Cacio]

Good morning,

I'm tryng to change some lines of code on the module called "CashOnDeliveryPlus" (COD+).

In my module i would like to set a maximum price, that will disable this method of payment when total to pay is greater than my maximum.

But when I try to change the file cashondeliveryplus.php, in B.O. I get two errors (one for missing class and one for parsing error).

I got the same errors also if I write only a new empty line in the original file, that's so strange.

 

How could I resolve my errors?

 

Thanks a lot, and sorry for my bad English