Can you tell me why was i limited to three returns when revenue canada says I have 20, I fill 4 returns a year.?

You can only use TurboTax Free software to prepare a maximum of four returns total. Two with a net income over $25k, and two with a net income below $25k.

With paid versions of TurboTax you can file the maximum paid for each version over $25k, and the remainder for free under $25k to a maximum of 20 returns as per CRA rules.