AVIS star alliance offer, but does not delivers

This is not what I ususally post, but I need to protest, becasue I received this email, from star alliance of the lufthansa, offering in 3 days renting a car by AVIS, the 3rd day was free. I am not brazilian and as member of the star alliance I received this on my birthday. So, I called the Avis in Goiania, GO. I asked for this offer and then they told me that I had to rent 4 days to get one day free. I agreed. Then in a 2nd call, they said that this is not valid in Brasil, but it is clearly stated that it is worldwide and it can happen in some special dates that would not be available, but this was not the case.
After numerous calls, I asked for the AVIS call center, to send me a written responce, why this offer was not aplicable, and I never received any email.
At the end, I decided, that I will never hire a car with AVIS, and hired a car with UNIDAS, a brazilian company that I already knew, which has much more advantages.
But still I think that this attitude should be comunicated to the star alliance, I do not want an offer, that they are not willing to deliver, or at least the terms should be clear.
bellow the original email I received


On Ter 18/05/10 09:20 , "Miles & More" mail@e.milesandmore.com sent:

Dear Mr Alximist,

Congratulations – you have gained your personal Miles & More birthday voucher with our virtual birthday cake.

You can redeem this voucher with our partner Avis and receive one free day when renting your car.* To use your voucher just:
- Book your rental car for a minimum period of three days at your local Avis station
- Please quote your voucher code TEAA010 when making a booking
- Take a print-out of this e-mail with you when you pick-up your rental car
- And the third day is free compliments

We hope you can use this voucher when you next rent a car with Avis and,
of course, continue to enjoy your journeys with Miles & More.

Yours sincerely,

Hubert Frach
Vice President Marketing
Deutsche Lufthansa AG

* This voucher entitles the holder to 1 free rental day in conjunction with a rental lasting at least 3 days. It is valid for the vehicle categories ‘small car’ (Group A) to ‘full size 4-door saloon’ (Group E), ‘compact class combi’ (Group H) and ‘compact class automatic’ (Group K). It is valid at all participating Avis offices worldwide and until 14.11.2010. Please book at least 24 hours in advance if you wish to redeem this voucher and specify your voucher code when booking. Please note that prepaid bookings or bookings made via any third party are excluded from this offer. Fees, localtaxes, optional insurances, supplementary costs such as charges for an additional driver and fuel, as well as costs for extra services such as, for example, refuelling or one-way rental charges, must be met by the renterand will be itemised separately on the invoice. The offer may not be used with corporate rates, other discount promotions or mileage offers. Vehicle groups vary depending on the country in which the vehicle is rented. The voucher is not valid on specific dates, depending on the country – please check on booking. This voucher is non-transferable and non-refundable. Renters must satisfy Avis’s requirements in terms of age, driving licence and credit worthiness.

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