Received email about this today from Towergaming, I have added a link it may be an affiliate and is nothing to do with me so feel free to ignore the link if you like. Not exactly setting the world on fire but looks easy enough.

Betting – Get a $7.00 Free Bet when you transfer $20 to your Betting account!
With over 30,000 odds on a busy day, Tower Gaming offers twice as many odds than the leading competitor! Add excitement to your favourite sports from all over the World with this Free Bet! Simply Deposit and Transfer $20 to your Betting account and a Free Bet of $7.00 will be ready for you to use right away! You're not required to wager any of the $20 you transferred! Transfer, Bet for Free, and Keep your Winnings!

VIP Bonuses

Free Bet Terms & Conditions
This promotion is only available to select new players on Tower Gaming.

In order to receive the free bet you must deposit/transfer a minimum amount of $20 into your Tower Gaming Betting account.

Your free bet can be used on any kind of single or multi-bet with odds of 1.80 or greater, with the following exceptions:
No free bets on Outrights
No free bets on Over/Under
No free bets on Asian Handicap

If you win, you will receive your net winnings. Net winnings are calculated using the following formula: (odds-1)* stake. The free bet stake value will not be returned to your account.
Example: You place $7 at odds 1.8 and win your bet. You will receive $5.60 in your account because (1.8-1)*7=5.6
Example: You place $5 at odds 1.8 and win your bet. You will receive $4 in your account because (1.8-1)*5=4

If you lose your bet, the free bet stake will not be deducted from your balance.

Duplicate accounts will not qualify for this offer. Any customer deemed to be taking advantage of this offer from multiple accounts will have all bonuses removed.

Your free bet can be placed at any time during the promotional period by selecting it on your betting slip. It does not have to be used on your first bet.

If you do not use your free bet before the end of the promotional period, it will no longer be available to you.

The entirety of your free bet amount must be used in one bet. Any remaining amount you do not place will immediately be lost.
Example: You choose to use your free bet on a stake of $1. In this case you will lose the remaining $6 of your free bet.