Is sixt.es Safe?

Company, or the SEO company they hired spammed a link advertising their website on my website without my permission and I had to waste my time removing their linkspam. Below is an email received from their marketing agency after google penalized them for linkspamming: "Dear Sir/Madam, I am Luis from Sixt Rent a Car. I contact you because we are attempting to remove certain links made by agencies who previously worked with us. One of these links has been posted on your site directory and unfortunately we are unable to remove it without your help. For this reason, could you please remove the following links referencing www.sixt.es ? xxxxx Thank you for your understanding, Luis Nayar Online Marketing Spain Sixt GmbH & Co. Autovermietung KG Zugspitzstr. 1 82049 Pullach"