Dell has been holding my tablet for over 3 weeks

I originally send in my dell venue 8 pro for a lcd panel issue on 6/5/14, I get it back and the lcd issue is fixed, but part of the back case of the tablet is broken by the speaker, dell instructs me to send it back again on 6/13/14. I get it back with the problem unfixed and a letter stating that the "windows operating system was re-installed". They instruct me to send it out again on 6/20/14. It has been at the service depot ever since. I called on 7/2/14 And they said the part to fix it is on back order and will be in stock in 1-3 days. Call back on 7/7/14, this time they say 1-2 days at most I should have my tablet soon. Call back on 7/9/14, part is still not in please wait 1-2 more days. Part finally came in on 7/11/14, but has been on repair status since then. It took one day to fix the lcd panel, but it has been over 5 days to replace the back cover??? I'm a bit upset at this point and then the customer service rep says that he sees that I have called in several times and he doesn't want me to call back until I get the tablet and just please wait. I am tired of waiting, dell has not allowed me to use this tablet for over a month now, and can not give me a clear response on when I will get it back. Dell really dropped the ball on this one.