"Bolloxing up" is a colloquial term used to describe making a mess or screwing something up. It can be substituted with other phrases such as "botching," "mishandling," or "flubbing." These synonyms convey a sense of failure or ineptitude in executing a task or project. Other alternatives include "bungling," "blundering," and "butchering," all of which suggest that an action was taken with inadequate planning or execution, resulting in a negative outcome. Regardless of the word used, the message is clear - something went wrong and corrections or further attempts may be necessary to achieve the desired result.