This place is very popular among locals. We know that many exchange offices downtown are notorious for ripping tourists off. That´s why we basically don´t waste time and go directly to Exchange close to Old Town Square. Sometimes there are line ups but no worries, it pays back (literally). They offer very good rates.
You can be always sure you will get a fair rate. You don´t have to be afraid of any hidden fees or paying commission. If you download (print) their discount voucher and present it there, you will get VIP exchange rate, which is even better (in case you exchange amount higher than 1000 CZK).
Link to VIP exchange rate voucher: https://images.iexchange.cz/kupon.pdf