Version Problems CDR13 files.. help

Hi there,

I bought corel graphics suite X7. before we all worked with corel x3. so we have hundreds of cdr13 files. should not be a problem we thought to open them and work with them again.... BUT.... unfortunately we found out that there are some serious problems. for example is the perspective from some objects completely damaged and also the extrusions aren't correct any more. so we contacted ther corel support (really no help) they told us that they will forward that problem to the programmer.... we never got an answer or a solution for our serious problem. the only info was that we should change the file from cdr to cmx. but then there are still faults in the data!!! we are really angry about that. 

Soooooo... our question.... is here someone who has an idea to solve this problem? 

for better understanding here is a pdf where the problem is shown. the upper pic is the CDR13 file in CDR17 and below is the CDR13 file in CDR13

hope someone could help