Why is my refund a lot less than the calculator

Have submitted my tax with TaxTim, but just want to check if it is better to submit including expenses (Fuel, oil, etc) as I left it blank?
Why is my travel allowance tax return on Taxtim calculator very high, but when I did the calculation on SARS it works out a lot less?

As per the calculator page, your allowable expenses are capped at your total allowance amount. In other words, if your travel allowance is less than the total expenses, then you're only able to claim up to the allowance amount. In this instance, the amount SARS has adjusted to is correct.