Hi Charmi,
You are in luck , I am an HR Consultant so can give you some advise here
Unfortunately the CCMA doesn't like fixed term contracts, especially ones that run for longer than a short period such as 6 months- 1 year, and since she has been with you for over 2 years and the fact that she never signed the contact, may not be in your favour. They may rather see it as a permanent arrangement and that a retrenchment process should have been followed.
Do you have anything in writing where you advised her that she would no longer be needed end Dec and that she needed to start looking for work, as this could be then used as part of the consultation process ( you need to consult with the employee as well as pay severance)
In most cases the worst the CCMA awards is around 3 months salary and given that you are an individual employer rather than a company they probably wouldn't go that far.
You have two options:
1. Advise her in writing that she was advised that you would no longer have a requirement for her Services by end Dec 2012 ( give the various dates you discussed it with her, as your daughter will be moving to a school and you no longer require a nanny and that you have been advising her to look for alternative employment, also state that you have ensured her UIF is up to date and you are willing to pay her up until 14 December , but she can leave with immediate effect. You can also then pay her the severance pay (as the other ladies mentioned its one week for every year of completed service) and indicate that in the letter as well. If you include her final payment in the letter, you can insist she signed receipt for that in the letter before you pay her, that way she is confirming she received the payment and the letter.
2. Stick to your guns that its a fixed term contract, pay her out until 14 December, but get rid of her now, she sounds unreliable and if she goes to the CCMA prepare for the fact that they often take the side of the employee and you may have to pay out at a later stage.
Hope that helps