First off, really enjoying Second Life

However I am a bit stuck with an account issue. After upgrading to a Premium Account and buying land I found that my Land Tier does not credit me with the 512m2 allowance and I did not receive the 1000L$ for upgrading. Also my weekly stipend is varying - some weeks 300, some 400. I was advised by Live Help to contact Billing by email which I duly did.
My question is, having submitted email requests for assistance, how long should I normally expect to wait for a reply and if there is no problem will I be told the support request is closed?