Hi Anon,
This is a difficult question to answer without seeing your hair and the condition it is in now.
The answer I give you first is please do not attempt to do a home colour just now, it could damage your hair even more. May I suggest, being patient and using the very best deep penetrating hair treatments you can buy on the market. Give your hair a rest for at least three months, the longer you are patient the better the next blond or colouring result will be. The hair grows around one centimetre, about half an inch a month, in the summer it may grow a little faster due to the heat.
Build your hair structure back up so your hair will accept a hair colour, without your hair being in tip top condition any colour you use will fade into a less attractive colour after a few shampoos. I do hope your common sense will tell you that damaged hair will never give a 100% good colour result.
What you have written tells me that your hair structure is damaged from over use of several years of home colouring, which you say your hair is frizzy and has lost its natural shine. Going blonde from brown coloured hair is at best a risk, at our salon we would advise you to build your hair structure back up before using bleach, and if you decide not to wait we would ask you to sign a disclaimer form, meaning that you are forcing us to do a bleach process on damaged hair. In our salon stylists are instructed not to do bleaching services on damaged hair, and if a client is persistent they must sign a disclaimer form. In good salons that is the usual procedure.
Philip Kingsley's Elasticizer is an excellent product for repairing damaged hair, we use these products in our salon but you can also buy them on the Internet.
Try persevering for three months with the colour you have now. I do realise you are unhappy with your colour now but you need to be patient and live with what you have now and concentrate getting your hair condition back to health. This is the advice I give as a professional hairdresser. After three months I suggest you visit a top colouring salon and ask them to check your hair and skin condition first by applying a skin and hair test, this is usually done on the back of the ear for skin tests and the similar area for the hair. This would involve at least two visits but at least you should be safe from similar hair colour disasters. My main concern is that you stop using any colour for now and give your hair a rest, it is like a sickness which needs time to heal.