Its hard to challenge the law. Tanzania lacks principles of taxation in the consititution. So far i dont see the grounds of challenging the law.
Maana kuna other items that have been taxed excise duty for years and nobody complained. Example beer inakuwa taxed vat and excise apart from that sigara, juice, maji, soda etc.
The principle behind is that this duty inakuwa charged on services and items that are either harmful or considered luxurious. About all in all ni njia ya kukusanya kodi. Hizo sababu zao ni mbwembwe tu
The question is; is a sim card a luxury at this age?
With advancement of techology i think, a sim card is more of a need than a want.
But it all comes down to the reason for y the government wants to introduce the tax.
But u need to have the legal backing.
So we go back to the principle of taxation which we dont have.
The best thing u can do to challenge the law is by protest. The court wont saves.